A wheel loader is used in construction, and widely used to perform an excavation operation for excavating soil, sand or the like, a conveyance operation for conveying the excavated soil and sand, loading and unloading operations of loading and unloading the conveyed soil and sand to and from a freight vehicle, soil preparation for road construction, a snow removing operation, a towing operation, or the like.
In accordance with situations of the aforementioned operations of the wheel loader, a transmission control unit of the wheel loader detects a travel speed and a load of the wheel loader and may automatically control a transmission.
For example, when the wheel loader travels on an ascending slope and a large force is required to drive the wheel loader, the transmission may automatically perform a transmission operation by shifting a high gear (for example, shift stage 2) to a low gear (for example, shift stage 1) based on a condition in which a travel speed of the wheel loader becomes slower and a transmission load becomes high.
In addition, when the wheel loader performs an operation such as excavation, or the like, and the transmission load is increased due to the excavation operation in a state in which the travel speed becomes slow so as to perform the excavation operation, a kickdown may be performed by shifting the high gear to the low gear, for example, shifting the shift stage 2 to the shift stage 1.
However, in a case in which a transmission operation is performed by detecting an increase in transmission load during the operation such as excavation, a time point when the transmission operation of the wheel loader is actually performed is delayed from a time point when the excavation operation starts. That is, after the transmission load is increased as the excavation operation is performed, the increased amount of load is detected to be transmitted to the transmission control unit (TCU), and the transmission control unit performs the transmission operation by performing the kickdown of the transmission (TM), for example, from the shift stage 2 to the shift stage 1.
As such, in the method of automatically controlling the transmission in the related art, because there is a difference between a starting time point when the operation such as excavation starts and a transmission time point when the kickdown transmission is actually performed, for example, only after a certain period of time has passed at the beginning since the operation in the shift stage 2, the transmission result into the shift stage 1 is obtained. Therefore, because the transmission operation is performed during the excavation operation, an operator experiences difficulty that the whole work efficiency deteriorates.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.